Populations

Question 1

What are the characteristics of populations?

Answer 1

Density = number of individuals per unit area
Distribution = size, shape, and location of area occupied

Question 2

What is absolute density?

Answer 2

The number of individuals of a population per uni area
-eg. # of moose per hectare

Question 3

What is ecological density?

Answer 3

The number of individuals of a population per unit area suitable habitat
eg. # if moose per hectare forest

Question 4

What is dispersal?

Answer 4

The permanent movement of individuals, usually from one population to another

Question 5

What is gravity seed dispersal?

Answer 5

Large seed size
Short dispersal distances

Question 6

What is ballistic seed dispersal?

Answer 6

Explosive dispersal
Short dispersal distances

Question 7

What is wind seed dispersal?

Answer 7

Seeds with appendages
Short to long dispersal distances

Question 8

What is water seed dispersal?

Answer 8

Seeds with floating capabilities
Short to long dispersal distances

Question 9

What is animal seed dispersal?

Answer 9

Via ingestion and defecation or hooks
Short to long distances

Question 10

What is human seed dispersal?

Answer 10

Breeding and transportation
Short to long distances

Question 11

What can dispersal alter?

Answer 11

Alter species distributions and local population densities

Question 12

What are the two major categories of dispersal?

Answer 12

Immigration = movement into a local population
Emigration = movement out of a local population

Question 13

What responses do predators show in response to variations in prey density?

Answer 13

Functional response = increase/decrease in feeding rate short-term
Numerical response = change in density of predator populations in response to changes in prey density

Question 14

What are the drivers of numerical responses?

Answer 14

Reproduction
Dispersal (aggregative response)

Question 15

How does reproduction drive numerical responses?

Answer 15

Time lag between peak prey population and peak predator population
Non-synchronized dynamic between predator and prey
Lag due to time needed for predators to produce offspring

Question 16

How does dispersal drive numerical responses?

Answer 16

No time lag between peak prey population and peak predator population
Synchronized predator and prey dynamics
No time lag as species are highly mobile and can track prey across the landscape

Question 17

What is distribution limited by?

Answer 17

The physical environment and species niche requirements
A species can only exist in areas where its niche requirements are fulfilled

Question 18

How can organisms be distributed on smaller scales?

Answer 18

Distributed in patterns that are random, regular, or clumped

Question 19

What is small scale random distribution?

Answer 19

An individual has equal probability of occurring anywhere in the area
Neutral interactions between individuals, and between individuals and the environment

Question 20

What is small scale regular distribution?

Answer 20

Individuals are uniformly spaced through the environment
Antagonistic interactions between individuals or local depletion of resources

Question 21

What is small scale clumped distribution?

Answer 21

Individuals live in areas oh high local abundance, which are separated by areas of low abundance
Attraction between individuals or to a common resource; limited dispersal

Question 22

What are large scale distributions?

Answer 22

How populations are distributed over scales in which there is significant environmental variation
The individuals of many animal and plant species are clumped
The broader the niche, the wider a species large scale distribution is

Question 23

Why aren’t all species in all places?

Answer 23

All organisms have limited energy and resources
It takes extra energy to survive and reproduce in regions on the edge of their niche

Question 24

What do species expand their range in response to?

Answer 24

Climate change

Question 25

What is dispersal lag?

Answer 25

Phenomenon where a species have not had enough time yet to colonize an area but will eventually

Question 26

What is a metapopulation?

Answer 26

Made up of a group of subpopulations living on patches of habitat connected by an exchange of individuals Only exist when individuals can disperse from one population to another If no dispersal, not a metapopulation

Question 27

What is population structure?

Answer 27

Other demographic characteristics like age distributions, sex ratios, birth and death rates, immigration and emigration rates, rates of growth

Question 28

What is the relation between organism size and population density?

Answer 28

In general, population density declines with increases in organism size because of body scaling and metabolic demand vs resource availability

Question 29

What is the relationship between size spectrum and plants?

Answer 29

Relationship is dynamic in a plant's life stages Density decreases with increasing biomass (age) in a process called self-thinning due to competition among plants -seeding = high density -adult = low density

Question 30

What is the rarity of species influenced by?

Answer 30

Geographic range of species Habitat tolerance Local population size

Question 31

What are the combinations of rarity?

Answer 31

Common species Species with one aspect of rarity = somewhat vulnerable Species with two aspects of rarity = more vulnerable Species with three aspects of rarity = prone to extinction

Question 32

What are the IUCN red list categories?

Answer 32

LC = least concern NT = not threatened VU = vulnerable EN = endangered CR = critically endangered EW = extinct in the wild EX = extinct

Question 33

What are special concern species?

Answer 33

Particularly sensitive to human activities or natural events

Question 34

What are threatened species?

Answer 34

Likely to become endangered if limiting factors are not reverse

Question 35

What are endangered species?

Answer 35

At immediate risk of extirpation or extinction

Question 36

What are extirpated species?

Answer 36

No longer exists in Canada, but does elsewhere

Question 37

What are extinct species?

Answer 37

No longer exists anywhere in the world

Question 38

What are data deficient species?

Answer 38

Not enough information to access status

Question 39

What are life tables?

Answer 39

Bookkeeping device to track births and deaths in populations, from which to estimate survival

Question 40

What is the survivorship curve?

Answer 40

Graphic summary Pattern of survival in a population, based on life table data

Question 41

What is a cohort life table?

Answer 41

Identify individuals (cohort) born at the same time and keep records from birth Data is most accurate but often difficult to collect as they require tracking individuals

Question 42

What is a static life table?

Answer 42

Record age at death of large number of individuals over narrow window in time Requires accurate estimate of age at death

Question 43

What is age distribution?

Answer 43

Calculate difference in proportion of individuals in each age class Assumes differences in numbers from one age class to next due to mortality

Question 44

How are survivorship curves constructed?

Answer 44

Once a life table is obtained, the number of survivors on the y-axis and the age on the x-axis can be graphed

Question 45

What is a type 1 survivorship curve?

Answer 45

High survival of young Animals die at older ages Most vertebrates, humans, annual plants

Question 46

What is a type 2 survivorship curve?

Answer 46

Constant rates of survival Birds

Question 47

What is a type 3 survivorship curve?

Answer 47

Low survival of young Very few individuals make it to old age Fish, trees

Question 48

What does age distribution reflect?

Answer 48

History of survival, reproduction, and growth potential

Question 49

How can we use age distribution to understand species stability?

Answer 49

A population might be relatively stable if there are lots of young individuals to replace older, dying individuals Might be less stable if there are less young individuals because they die off

Question 50

How can we use age distribution to study climate problems?

Answer 50

Even distributions will indicate a steady climate Cohorts missing due to droughts are subsequence lack of reproduction or large cohorts due to wet year and lots of resources can indicate climate change

Question 51

What is sex ratio?

Answer 51

Relative frequency of each sex type in population

Question 52

What do population sex ratio changes depend on?

Answer 52

Relative fitness of different sexes

Question 53

Why are sex ratios usually equal?

Answer 53

Frequency-dependent selection = fitness of a genotype depends on its frequency Only females can reproduce = more females as time goes on